function _sdx(v){
	var i = document.getElementById(v).selectedIndex; return document.getElementById(v).options[i].value;
}

function set_date_hidden(id){
	var val = _sdx(id + '_yyyy') + '-' + _sdx(id + '_mm') + '-' + _sdx(id + '_dd');

    if(document.getElementById(id+ '_hour') && parseInt(document.getElementById(id+ '_hour').value)){
        val += ' '  + _sdx(id + '_hour') + ':' + _sdx('_min');
    }

    document.getElementById(id).value = val;
	if(typeof set_date_hidden_callback == "function") {
		set_date_hidden_callback(id);
	}
}